Frequency of supernumerary limbs following blastemal rotations in the newt

Abstract

Experiments on the newt, Notophthalmus viridescens, showed that 180" surgical rotation of the forelimb blastema could provoke supernumerary limb formation (Bryant and Iten, '76). The polar coordinate model predicts a high incidence of supernumerary limbs for angles of rotation at or near 180" and no supernumeraries for small angles of rotation. The results of recent experiments on axolotls (Maden and Turner, '78; Wallace, '78; Wallace and Watson, '79, Turner, pers. comm.), however, do not exhibit this pattern. In the majority of these experiments, supernumerary limbs could arise from any region of the limb circumference. The experiments described in this paper consist of a comprehensive series of ipsilateral rotations of newt forelimb blastemas performed at increments of 45" between 0" and 360". MATERIALS AND METHODSAdult male newts, Notophthalmus viridescens, obtained from Bill Lee's Newt Farm, Oak Ridge, Tennessee were used in these experiments. They were maintained at 25" 2 1" C, except as indicated below, and exposed to a 12-hour light cycle. Prior to any surgery, animals were anaesthetized by immersion in 30% chlorobutanol (Sigma). Both forelimbs of the newts were amputated at the level of the midhumerus and allowed to regenerate to the stage of three or four early digits (Iten and Bryant, '733. Each stump and blastema was then marked with a thin line a t the middorsal position (Fig. 1) using a drawn glass capillary and biological grade marking ink (Pelikan). These reference ink marks were used to position the blastemas and to subsequently monitor their orientation. Blastemas were amputated a t their interface with the stump, rotated by a specified angle, and replaced on the same stump as shown in Figure 1. To help hold each blastema in place during the initial stages of healing, small pieces of lens tissue were positioned alongside the grafts. When each operation was completed, the animal was positioned on a small cotton support in an individual finger bowl and placed in a refrigerator (-5" C). One day later, the cotton was removed, the newt was revived by immersion in cold water and left in the refrigerator for an additional three to four days to reduce activity and minimize graft loss. When removed from the refrigerator, animals were maintained individually at room temperature (15-20" C) and closely observed for signs of graft regression or derotation. After seven to ten days, animals were grouped in battery jars and placed in an incubator at 25" C. Each animal was examined once or twice per week until the graft and any supernumerary limbs were at the stage of late digits (usually about two months after grafting), at this time the limbs were fixed in Bouin's solution, stained with Victoria blue B, and cleared for skeletal analysis (Bryant and Iten, '74). No limbs with blastemas that regressed beyond

Looking proximally and distally: 100 years of limb regeneration and beyond

“…Meanwhile, several other investigations had reported that up to three supernumeraries arise after APDV rotation over a wide range of angles (Wallace, 1978;Maden, 1978b;Wallace and Watson, 1979), though the maximum frequency of formation was at 180 , falling off on either side (Stock et al, 1980;Turner, 1981). Furthermore, the loci of origin of these limbs were unpredictable.…”

Cryogels: Morphological, structural and adsorption characterisation

“…Notice that the mobility of bacteria was studied using PCS in detail [209,[218][219][220][221][222]. This ability of PCS is of importance in respect of elucidation of the influence of media or cryogel membrane or scaffolds on living microorganisms.…”

Υπεραριθμοι Αναγεννητικοι Σχηματισμοι Κατα Την Οντογενεση Του Ακρου Στο Ανουρο Bufo Bufo

“…Το μοντέλο όμως δεν μπορεί να εξηγήσει την εμφάνιση υπεραρίθμων στις διάφορες περιοχές της περιφέρειας μετά από περιστροφές μικρότερες ή μεγαλύτερες από 180 (Maden and Turner,1978;Stock et al,1980;Wallace and Watson,1979), ούτε τη δημιουργία συμμετρικών ως προς τους εγκάρσιους άξονες άκρων ή μεικτών μετά από περιστροφή 180 (Tank ,1981;Maden,1982;Maden and Mustafa,1982b;Papageorgiou and Holder, 1983). Επιπλέον αποτελέσματα μετά από περιστροφή 90 (Stock and Savage, 1978a, b;Maden, 1982Maden, ,1983a δεν επιβεβαιώνουν τις αρχές του μοντέλου.…”